666565666 has 32 divisors (see below), whose sum is σ = 1097929728. Its totient is φ = 301631040.

The previous prime is 666565663. The next prime is 666565681.

It is a happy number.

666565666 is nontrivially palindromic in base 10.

It is not an unprimeable number, because it can be changed into a prime (666565663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 771951 + ... + 772813.

It is an arithmetic number, because the mean of its divisors is an integer number (34310304).

Almost surely, 2^666565666 is an apocalyptic number.

666565666 is a deficient number, since it is larger than the sum of its proper divisors (431364062).

666565666 is a wasteful number, since it uses less digits than its factorization.

666565666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1426.

The product of its digits is 6998400, while the sum is 52.

The square root of 666565666 is about 25817.9330311317. The cubic root of 666565666 is about 873.5363464036.

The spelling of 666565666 in words is "six hundred sixty-six million, five hundred sixty-five thousand, six hundred sixty-six".